From automotive technology, automatically shifted transmissions are known. On the one hand there are transmissions in which a shift-under-load element is associated with each gear. Furthermore, there are also transmissions which consist in principle of at least two part-transmissions that can be shifted in parallel, each of which has at least one shift-under-load element and a series of positively-interlocking shifting devices. In any part-transmission that is free from load at the time, gears can be prepared by engaging the shifting devices for the later gearshift process. The shifting devices are actuated with the help of external energy sources, for example hydraulically, electro-mechanically, electromagnetically or pneumatically. A shifting error in the transmission, for example when due to a control error two shifting devices are actuated simultaneously by the actuating devices, which mutually block one another, can result in failure of the transmission or even in a reduction of the driving stability.
In known transmissions with interlock-type shifting devices this is prevented for example by mechanical blocking. However, to produce transmissions which are as compact as possible, it makes sense to position the necessary actuating devices directly in the vicinity of the shifting devices to be shifted. But if each shifting device comprises an isolated actuating device, the mechanical blocking required is very elaborate and therefore occupies considerable space and is cost-intensive. And for example, in a transmission in which the actuating devices are arranged in the form of electric motors in the transmission shafts, no mechanical blocking is possible.